1. Field of the Invention
The present invention relates to an integrated optoelectronic module, and more specifically, to an integrated optoelectronic module that is used for a high-frequency photodiode.
2. Description of the Related Art
A photodiode intended for high frequency operations within a THz frequency range of 0.3 THz to 3 THz needs to have a small device capacitance and thus requires a reduced junction area. This is because the level of degradation of responses associated with an RC time constant increases consistently with frequency and because the width of a depletion layer inevitably needs to be reduced in order to make intrinsic responses of the photodiode faster, that is, to shorten an internal carrier transit time, leading to an increase in capacitance per unit area. A basic constraint in this case is that a reduced device size decreases an upper limit on a possible operating current for a photodiode according to the junction area.
Thus, a large number of photodiodes each with a very small junction size needs to be arranged in an array to combine power from the individual photodiodes to increases general power (power combiner). Several methods are available for inputting optical signals into the arrayed photodiodes. However, when the photodiode has a reduced junction size, the conventional technique involves many problems with a packaging technique for the arraying, an optical coupling technique required for the arraying, and the like.